Different types of push-in fasteners are known for use in different environments and for different purposes. A common feature in push-in fasteners is a resiliently bendable or deflectable retention member that bends inwardly when the fastener is inserted through a hole or aperture and that rebounds outwardly to hold the fastener when the fastener is fully inserted. Inward bending of the retention member can be caused by the sliding engagement of the member against the aperture surface in the component as the fastener is inserted through the component.
U.S. Pat. No. 5,301,396 discloses a fastener assembly with a compression member. The fastener assembly includes a fastener having a shank with a head at one end of the shank, with the shank comprising a plurality of resilient legs integrally formed with the head and mutually connected opposite the head at a distal end of the fastener. The legs are bowed outwardly to define a maximum diameter larger than an aperture size in a panel or panels or component or components through which the fastener will be inserted. Accordingly, during insertion, the legs deflect inwardly so as to pass through the aperture(s) and rebound outwardly as the maximum diameter portion passes through the aperture(s). The fastener assembly further includes a compression ring having a central tapered aperture with a diameter slightly less than the diameter of the aperture in the panel(s) or component(s) through which the fastener is inserted. When used as a part of a fastener assembly, the ring rests against the panel(s) or component(s) through which the fastener is inserted as the fastener is inserted. The ring provides contact against the legs, compressing the legs for passing through both the ring and the panel(s) or component(s). The slightly smaller diameter of the aperture in the ring holds the legs away from sliding contact against the edge of the aperture in the panel or component, which may be abrasive to the material of the fastener. Accordingly, the ring is useful in reducing drag or abrasion that may occur if the aperture of the panel or component is harsh or abrasive to the material of the fastener. The ring and fastener can be made of purposely selected materials and shaped in a manner so as to slide easily against each other, thereby reducing insertion force required when compared to the force required if the legs were to slide directly against the aperture(s) of the panel(s) or component(s) in which the fastener is used. However, due to the shape and positions of the legs in the ring, more drag occurs in some areas of contact against the ring than in other areas of contact, or in areas where the legs do not contact the ring. According, the shape of the ring can become distorted during insertion, causing installation difficulties.
The aforedescribed fastener assembly has been used effectively to reduce insertion force even with fasteners that provide high retention by having a relatively high extraction force requirement to remove the fastener. However, it is desirable to further reduce insertion force required in some situations, and/or to provide a pre-installation arrangement of the ring on the fastener that is secure during handling so that the ring does not become separated from the fastener inadvertently.